The implantation or insertion of medical devices into the body of a patient is common in the practice of modern medicine. For instance, over the past few years, stents (i.e., devices which are expanded inside blood vessels to increase blood flow in areas blocked by plaque) have emerged as a prime therapy for atherosclerosis. Unfortunately, in-stent restenosis may occur in some instances (e.g., as a result of injury to the vessel wall). Drug eluting stents have a polymeric coating over the stent to release a drug at a prescribed rate for a given duration to counteract the effects of in-stent restenosis. The coating on the stent is in contact with the delivery system (e.g., balloon) along its inner diameter and in contact with the vessel wall along its outer diameter. Examples of drug eluting coronary stents include commercially available stents from Boston Scientific Corp. (TAXUS, PROMUS), Johnson & Johnson (CYPHER), and others. See S. V. Ranade et al., Acta Biomater. 2005 January; 1(1): 137-44 and R. Virmani et al., Circulation 2004 Feb. 17, 109(6) 701-5.
Various types of polymeric materials have been used as drug-releasing reservoirs, including, for example, homopolymers such as poly(n-butyl methacrylate) and copolymers such as poly(ethylene-co-vinyl acetate), poly(isobutylene-co-styrene), for example, poly(styrene-b-isobutylene-b-styrene) triblock copolymers (SIBS), described, for instance, in U.S. Pat. No. 6,545,097 to Pinchuk et al., and poly(vinylidene fluoride-co-hexafluoropropylene), described, for instance, in Pub. No. US 2008/0004695 to Stewart et al.